Concrete slab



M. DEUTSCH CONCRETE SLAB Filed Reb. 26, 1937 3 Sheets-Shut l lNVENTOR TRNEYS.

'Mmh 5, 1940.

m. m. m1.

March 5, 1940. M. DEUTSCH 2,192,182

CONCRETE SLAB Filed Feb. 26, 1957 3 Sheets-Sheet 5 l., INVENTOR ATToRNEYa y Patented Mar. 5,1940

UNITED STATES PATENT OFFICE Maurice Deutsch, NewYork, N. Y. Application February 26, 1937, Serial No. 127,888

16 Claims.

VThis invention relates` to cellular reinforced concrete slabs and particularly to that type which are cast horizontally and subsequently used as wall, floor, partition or roof elements in the erection of lso-called prefabricated buildings.

The principal objects of the invention are to provide a slab of this type having improved, permanently positioned hollow core members which form the cellular openings and which cooperate with other elements of the slab toincrease its strength, to reduce its weight, and to lessen the cost of its fabrication; to completely insulate yfrom each other, both thermally and acoustically, the two sections of such a slab'at opposite sides of a median plane thereof, and to provide throughout for the expansion andvcontraction of such sections toward and away'from each other and in a shearing fashion; to provide y a waterproof seal between the two sections of the slab at all points where moisture or dampness might otherwise penetrate to the inner section of the slab; and to provide improved fastening means for securing the completed slabs together when erectingla building.

f. Other objects will appear from the following description.

Several forms of the improved building slab,

and also the method of making/it, are illustrated in the accompanying drawings, in which 30 Fig. 1 is a horizontal section through a wall slab and a portion of an adjoining one, the section being taken on the line I-I of Fig. 15, in such a plane as to include, and show the construction of, the Yfastening means for securing the slabs together;

Fig. 2 is a similar horizontalI section through the adjoining portions of the slabs shown in Fig.- l, the section being taken on the line 2--2 of Fig. in a plane where the fastening means does not occur;

Fig. 3 is a vertical section 3-3of Fig. 1;

Fig. 4 is la section taken on the line l-I of Fig. 3, the core members which form the cellular openings being omitted to show the manner in which the metallicffastening elements are associated with the reinforcing struts;

Fig. 5 is a vertical section through one of the slabs as it appears on the casting table, and illustrates the method'of casting it;

Fig. '6 is a partial horizontal section through a completed slab and shows a modiiicationof the strut illustrated immediately above it in Fig. 1; i Fig. 7 is a horizontal section ,taken on the line o takenon the line u 1-1 of Fig'. 1 5, and illustrates the man er in which the wall slabs may be fastened together at the corner of a building;

Fig. 8 is a vertical section taken approximately on the line 8-8 of Fig. 5, and illustrates the fastening means at the upper and lower ends of 5 the slab shown in Figs. l and 5;

Fig. 9 is a similar section taken on the line 9-9 of Fig. 5; .Y

Fig..l0 is a vertical section ltaken on the line IIJ-Ill of` Fig. 13, and also on the line llll0 of 10 Fig. l2, through a portion of a slab on the casting table, the slab in this case being particularly adapted for use as ya floor slab;

Fig. 11 is'a vertical section of the same slab taken on the line II-II of Fig. 13, and on the 15 line II-II of Fig. l2; l

Fig. l2 is a section taken on the line l2-I2 of Fig. 10 and on the line l2-I2 of Fig. 13;

Fig. 13 is a plan view of one corner of a floor slab as it appears on the casting table, the purpose of this view being mainly to show where the sections of some of the other lfigures are taken;

Fig. 14 is a d tail perspective view of a portion of one of the metallic reinforcing struts illustrating the manner in which the fastening means shown in Figs. l0, l1 and 12 is associated with it;

Fig. l5 is a schematic representation in perspective of a portion ofv a building constructed from slabs made in accordance with the invention;

Fig. 16 is a vertical section taken on the line IS-IB of Fig. 15 through a portion of a building constructed of slabs made in accordance with 'the invention and illustrates the manner in 35 which the floor slabs may be` fastened to the wall slabs;

Fig. 17 is a section taker*` on the line I1-I1 of Fig. 16, and on the line ll-I'l of Fig. 15;

Fig. 18 is a horizontal section taken on the 40 line |8-l8 of Fig. 17, and

Fig. 19 is a vertical section illustrating a modified way in which the floor slabs may be fastened to the wall slabs.

The wall slab shown in Fig. 1, comprises in general a body of concrete cast around a series of hollow core members or forms left permanently in the slab. Between adjacent'core members, and at the ends of the slab, the concrete forms struts, butthe transverse continuity of these struts is interrupted by interposed waterproof insulating and expansion material so that the slab is divided along a median plane ,into an inner `section and an outer section. The ,two Y sections of the slab are tied together by metallic y transverse reinforcing struts embedded in the concrete struts. 'I'he two sections of the slab are reinforced by metallic members extending through them and which span the reinforcing struts and lle outwardly of the'core members. Metallic fastening elements rigidly secured to certain of the strut reinforcements are cast within the slab at suitable point'sto enable the slabs to be bolted together.

'I'he concrete forming the inner section is shown at I and that forming the outer section is shown at 2. At the ends of the slab and at spaced intervals there is a concrete strut 3. Metallic reinforcing struts 4 are embedded in the concrete struts. All elements that make up one of these reinforcing struts are rigidly secured together or otherwise made unitary, as will later appear. Metallic bars, or so-called flats 5, spaced every few feet apart are welded or.otherwise rigidly secured to the upper edges of the reinforcing struts 4 and extend through the concrete of the upper section in a direction parallel with the upper face of the slab. Similar bars secured to the lower edges of the reinforcing struts 4. likewise extend through the concretev of the' lower section. The upper bars 5 support and have welded or otherwise secured to them a layer of wire mesh 6, and likewise a layer of wire mesh is secured to the lower bars 5. The bars v5 and the wire mesh`6 reinforce the concrete forming the inner and outer walls of the slab. It will now vbe noted that all of the metallic reinforcing elements are rigidly connected together to make the entire reinforcing structure continuous and unitary.

A hollow core member is located between each pair of reinforcing struts 4. lEach core member comprises two independent opposing strips of waterproofed fibrous material I and 8, which extend longitudinally between the reinforcing struts.

The two sheets are transversely arched outwardly and the edge portions lie in close proximity as indicated at 9. Each stripy is of such a width that it extends substantially the entire distance from one reinforcing strut to the next one. Each pair of opposing sheets form a tunnel like passage or opening extending vertically through the slab. The number of core members forming the openings in the slab may be varied to suit requirements. vThere may be one or more. The span of each core member may approximate 4 so ordinarily there wil1\be several core members in one slab.

The opening at the upper and lower ends of the hollow core members is closed by two fiat sheetsv of waterproofed fibrous material `Ia and 8 (Fig. 8), the sheet Ia cooperating with the lower core sheet 'I to close the lower part of the passage and the sheet 8a cooperating with the upper core sheet 8 to close the upper half of the passage. Interposed between the adjacent edge portions 9 (Figs. 1 and 2) of the fibrous core sheets is a layer of plastic non-hardening waterproof `material I0, such as thick mastic or a mixture of similar plastic material and fibers. At the extreme ends of the slab the edge portions 9 of the fibrous lsheets are extended or supplemented beyond the last reinforcing strut 4 as shown at 9 in Fig. 2, and the non-hardening material I0 is likewise extended between them so that both the fibrous material and the non-hardening material will extend to the extreme end of the slab. Likewise, at the upper and lower ends of the slab (Fig. 9) a layer of non-hardening material It) lying between waterproofed fibrous sheets 9 is sandwiched between the end sheets Ia and 8l v and away from each other and with a sliding or p shearing action one upon the other, and the brous material cooperates with the non-hardening material I I) to insulate the two sections of -the slab from each other both thermally and acoustically. Moreover, the non-hardening material I0 cooperating with the waterproofed fibrous sheets between which it'lies `acts as a seal and prevents moisture or dampness from reaching the inner section of the slab at all points. The reinforcements 4 'embedded in the concrete struts, of course, tie the two sections of the slab together. l

The inner face of the slab has a layer II of any suitable material that may serve as the interior finish of the building, such as Keene'cement, acoustic plaster, or the like, and the outer surface of the slab has a layer I2 of any suitable material that is adapted for the exterior" finish of the slab. This layer may be finished to resemble brickwork, stone, wood siding, or to` give any effect desired.` v

Before proceeding with a- `description of the fastening means for securing the slabs together when erecting a building, it should be noted thatV each reinforcing strut 4 comprises an I-shaped member whose web has been expanded, as best shown in Fig. 14. (This gure, however, shows the fastening` meansl for the floor slabs to be hereinafter described, -and not the fastening means for the wall slabs now to be described.) This results in two T-shaped bars with diagonals connecting the central flange 4 of one .T-bar with the central flange 4 of the other l`bar.

them, as by welding, apair of angle irons I3 which The end strut reinforcements have secured to extend transversely of the slab and bear against y the inner face of the central anges 4 of the T- shaped bars (Figures 1, Band 4). A metal strap I4 is welded or otherwise secured to thevangle irons I3. The web of this strap is provided with an opening I5 (Figure 4) which is slightly elongated vertically. A tube I6, preferably of fibrous.

material, having the same cross sectional shape as the opening I5, extends from the perforated web of the strap I4 through the concrete to the end of the slab. The face of the strap I4 and its opening I5 are accessible from the interioro one of the core openings.

When it is desired to bolt two of the slabs together in erecting a wall, -the edge surfaces of the slabs are placed in abutting relationV as shown at the right in Figure l, and a bolt II is inserted through the tubes I6. When nuts I8 at the extremities of the bolt are tightened, the slabs are retracted tightly against each other. Of course the bolt I'I may have a head-at one end in place of the second nut shown in the drawings. As best shown at the left in Figure-l, the

meeting edge surfaces of the slabs are preferably shaped to provide a recess I9 extending vertically down the edge of the slab. VThis recess has a deeper central recess IL` Atk each side of the recess I9 is a small recess 2| which extends par- 4 allel with the recess I9 When two slabs are positioned prior to bolti'ng, a key member 22, shown at the right'in Figure 1, is inserted between the central vrecesses 20. This key member may be cast from concrete or anyl other suitable material and has an opening to accommodate the bolt I`I. A packing 23 of waterproof non-hardeningmaterial, such as mastic, or a mixture of a similar plastic material and fibers, is inserted in the shallower recess I9 at each side of the key 22. This packing also serves as a yielding joint topermit expansion and contraction oi the.slabs relative to each other. Caulking' cords 24 are placed in the recesses 2I. It will thus be seen that when the slabs are bolted together, a tight waterproof expansion joint is effected. If desired thekey 22 may be cast integral with one of the slabs. i

In order to permity insertion of the bolt' `I`I and tightening of the nuts on the bolt, the inner section of the slab is provided with a hand hole 25 near each of the fastening assemblies. The hand hole communicates with the particular core opening through whic-h the corresponding fastening assembly is accessible. The fastening assembly lies wholly within the vslab and access to the interior of the'slab, made possible by the hand holes 25, enables the slabs to be bolted together.

It should be particularlynoted that the reaction of the clamping bolt is not directly against the concrete. The fastening bolts retract the straps I4 against the angle irons I3 and these in turn are retracted against the, webs 4 of the strut reinforcement 4. Thus the clampingstrains are all taken up by the metallic reinforcing structure.

Fastening assemblies such as those shown in FigrQl preferably occur near the upper corners of the Wall slabsl and near their glower corners as diagrammatically indicated at-26 and2'I inFig. 15. Fig. 2 is a section through the joint shown at the right in Fig. l taken in a plane where no fastening assembly occurs, for instance, on the line 2-2 of Fig. l5.

Wherever a fastening assembly occurs, the ex-v pansion and waterproof material IIJ abuts against the fibre tubes I6 as shown in Fig.. 3, and the fibrois core sheets are slotted to receive the flanges of the straps, I4. The elongated opening I5 in the strap I4 and the elliptical shaped tube through which the bolt II 'passes provides enough play or tolerance to permit a slight vertical movement of one slab relative to the adjacent one.

Wherever greater strength is required at the concrete struts, two metallic reinforcing struts 4 may be employed therein as shown in Fig. 6. In other words, the strut shown in Fig. 6 may, if desired, be substituted for the strut shown immediately above it in Fig. 1. In this case the edge portions of the fibrous core sheets are ex tended or supplemented between the metallic struts as indicated at 9' and thetnon-hardening material III is extended between them.

The method of casting one of the improved` slabs is illustrated in Fig. 5. A casting table of any suitable type maybe employed having a horizontal surface A and sidewalls B forming a I mold of the desired sliape andsize. Forms C of the proper configuration are utilized to impart the desired shape to the surfaces of the slab that are to mate with corresponding surfaces on other slabs. 'I'he first step'is to deposit a layer of Keene cement or other material II that is tov constitute the interior finish of the slab. A layer of concrete is then deposited up to the level indicated at D. The entire metallic reinforcing .inforcing structure may be positioned atan earlier stage 'and the concrete forced through under and around the part that is to be embedded. The sheets 1 constituting the lower halves of the core members, and the end closure sheets Ia (Fig. 8,) are nowpositioned and held in place in any suitable manner while more concrete is forced in to completely fill the space around the lower half of the cores up to the level indicated at F. Wherever necessary the edge portions of the fibrous core sheets may have slots or openings 28 to allow the concrete to be introduced through them. The lower fibrous core sheets are supplemented wherever necessary as indicated at 9' in Figs. 2 and 6 and at 9" in Fig..

9 and then the layer of non-hardening material I0 is applied at all places where it is to occur'. It will be understood that appropriate forms are employed to form the hand holes 25 in the lower section of the slaband to` provide any other desired openings to receive heat registers, ventilators and the like, and that all `necessary door and window frames may be set in place before pouring the concrete. Also during thecast ing of the lower section of the slab, accessory elements such as pipes, conduits, lighting fixtures, or similar devices represented at129, and which are to extend transversely through the lower section of the slab, are positioned, and if the slab is to be provided with bolts or similar accessory elements represented at 30, for attachment to interior devices when the building is erected, tubes 3I may be cast in place to receive them. It is important to note that at this stage during casting of the slab only the lower halves of the core members have been positioned and that the interior of the core members is still accessible. This makes it possible to perform at this time those operations in the interior portion of the completed. For instance, the transverse pipe or conduit 29 may at this time besuitably connected with a pipe or conduit 32 that is to pass vertically through the wall slab, and the bolts 30 may at this time be inserted in the tubes` 3I until they rest on the surface of the casting table. When the slab is subsequently removed from the casting table, the bolts 30 may be drawn through the tubes and thus made to project into the interior of the building for attachment to the appropriate devices. Moreover, by completing the lower section f the slab before-the upper halves of the core members are positioned and before the concrete forming the' upper slab section is poured, it can be definitely ascertained that the concrete has reached all points under and around the lower halves of the core members, thus insuring that no voids or open spaces will be left in the concrete.

The fibrous sheets 8 constituting the upper halves of the core members and the end closure sheets I!a are now positioned and supplemented structure, including the fastening assemblies, is now positioned in the mold. If desired the upper wherever necessary as at 9 in Figs. 2 and 6 and and around the .upperr halves of the cores to the level indicated at G. If the span of the core members happens to be quite long, or if the brous material does noty have sufficient strength of itself to support the weight of the concrete above it, the upper halves of the core members may be reinforced in any suitable way to prevent them from collapsing, when concretev is poured over them as by the use of llprops, supports or braces positioned inside the core members orr positioned over the upper halves of them. The upper bars and the wire mesh 6 are now welded to the upperredges of the reinforcing struts 4 if theywere not in place when the rest`of the reinforcing structure was positioned. More concrete is then deposited to bring the level to the plane indicated at H, and nally the material I2 for the exterior finish of the slab is deposited and finished ofi" in the desired way. It will be understood that the casting table may be vibrated at any stage of the process. Also to facilitate hardening and'curing of the mass heat or vacuum may be applied at any stage. After the slab has been allowed to set, it is removed from the casting. table and is ready for use in the erection hand slab is provided with a special fastening 'assembly to cooperate with the fastening assembly in the righthand slab and which has already been described. In the lefthand slab additional reinforcing struts 4 and 4b may be employed and angle irons I3 similar to those shown at I3 in the other figures may span the flanges of the reinforcing struts 4 so that they will lie substantially parallel with the corresponding angle irons I3 in the adjacent slab. 'A strap I4' reacts againstthe angle irons I3"in the manner previously described, and the bolt I1 reacts against the strap I4' and the strap I4 in the other slab when the joint is made. The end portion 'of the lefthand slab in Fig. 7 mayfhave a small hollow core member 1-8 corresponding in` general with the core members previously described, and the waterproofing-and expansion material II'I is interposed, as shown', between the inner and outer sections of the slab 'and extends to the end thereof. If desired, the extreme end of the slab may have applied to it a coating of waterproof cement finsh or the like 33 which conceals the expansionV material I0 and provides an exterior finish at the end of the slab.

'Ihe upper and lower ends of the wall slab shown in Figs. 1 and 5 may be provided with fastening assemblies to enable the upper and lower edge surfaces of the slab to be bolted to iloor slabs. As these additional fastening assemblies do not show in the sections of Figs. 1 and 5, they have been illustrated in Figs. 8 and 9. These figures are sections taken in a plane substantially at right angles tothe plane of Figs. 1 and 5, the section of Fig. 8 being taken; on the line 8-18`of Fig. 5 and the section of Fig. 9 being taken'on the line 9 9 of Fig. 5. It will be understood that these figures show the fastening assembly at only one end of the slab because the fastening assembly at the other end may be identical in construction as will later appear from the description of Fig. 16. In this case a metal plate 34spans the central flanges 4' of the reinforcing strut and is welded or otherwise secured to them. One ange .35 of an angle' plate is welded or otherwise securedto tht.` plate 34 so that its other iiange 36 lies parallel with the edge surface -of the slab to be bolted to the oor slab. Flange 36 is perforated to receive the vend of a fibre tube 31 which is suitably held in place during casting of the slab. This tube receives the bolt that clampsthe slabs together.

'Ihe floor slabs may be substantially the same l in (construction as the wall slabs already described the principal difference being in the construction and location ofthe fastening assemblies. Figs. 10, 11, 12 and 14 illustrate one form of fastening means for the floor slabs. In the case of the floor slabs the clamping bolts, one of which is preferably -located near each corner of the slab, extends vat right angles to the upper and lower faces of the slab, and lthus the fiber tubes which receive the bolts should also extend in this direction. This is accomplished by welding or otherwise attaching a U-shaped channel 38 to a plate 39 .which spans the centralA anges 4 of the reinforcing strut and is welded or otherwise secured tothem. 'Ihe liber tubes 46 which receive the clamping bolts fit in perforations in the flanges of the\channel member 38 and are suitably held'invplace during casting of the slab. During casting of the floor slabs, forms 4I and 42 may be employed to give the kproper shape to the faces of the floor slab where they meet the edge surface of the wall slabs to receive the key y22, the' packing or expansion material 23 and the caulking cords 24.

For a better understanding of lthe assembled slabs shown in Figs. 16 and 17, it will be helpful at this stage to point out again just` where the fastening assemblies on the various slabs occur. By reference to Fig. 15 it will be seen that the fastening assemblies for the vertical meeting edges of the wall slabs occur approximately at the points indicated' at 26 and ,21, while the fastening assemblies for the horizontal meeting surfaces between the wall slabs and the floor slabs, or between the roof andfloor slabs, occur approximately at the places indicated at 43, 44, 45 and 46. Fig. 16 is a vertical section taken approximately on the line I6-I6 of Fig. 15, through the fastening'assemblies for the floor and wall slabs, looking toward the joint ybetween the wall slabs which joint lies -just tothe'rear of the plane of the section. Fig. I'Tis al section taken on the line I1-I1 of Fig. 15, and also yon' the line Figs. 16 and 17 it will be seen that in assembling the wall and floor slabs, and also the roof slabs (which may be constructed substantially like the slabs hereinbefore described), bolts yI1 are .Y

inserted through the fiber tubes 40' of the oor slabs and the corresponding fiber tubes 31 of" I1-I1 of Fig. 16. Now referring to' be fastened directly to the lower edge surfacel of Y the superposed wall slab by fastening means on bothof these slabs similar to that shown in Figs. 8 and 9. Near the upper edge of the lower wall slab a metal plate 41 may be welded to the'l reinforcing struts so that the outer surface of the plate will be substantially flush with the interior surface of the slab. Angle irons 48 welded to the plate 4l provide 'horizontal ledges 49 which support theend ofA the floor slab. Another plate 41 and angle irons 48 may likewise be secured to the reinforcingstruts near the lower edge of the superposed wall slab so that the lfloor slab liesv between the horizontal flanges 49 ofthe upper angle irons and the horizontal flanges 49 of the lower angle irons. The fastening assembly at the end of the floor slab may be substantially like that shown in Fig. l6`. When the floor slab is positioned, the bolts are inserted through the ber tubes 'offl the door slab and through the perforations "in the horizontal flanges 49 and 49, of the angle iron's 48 and 48'. Any portions of the' fasteningl means which would ordinarily'be exposed in the interior of the building may be concealed by copings or llets or other architectural expedients indicated at 50. If the passages formed in the slabs are to be' utilized as ducts for Ventilating purposes, or for conveying hot air, or to receive pipes or conduits, the concrete of the wall slabs, where they join may be provided with openings or passages 5I, and if the passages in the wall slabs are to communicate with the passages in the floor slabs, theA concrete at the end of the floor slabs,` and at the adjoining faces of the wall slabs, may be provided with openings 52. Similar openingsv may be provided in the slabs shown in Fig. 16 to establish communication between the passages in the wall slabs and those in the floor slabs.

It will now be noted that in every case the slabs are bolted together by clamping metal to metal. In other words, the clamping forces of the bolts are transmitted directly to metallic elements which in turn transmit them to the unitary metallic reinforcing structure. This also causes the metallic structure throughout the building to be substantially continuous. 'I'he fastening instrumentalities may be entirely concealed within the slabs thus leaving no project- 4ing members on the exterior or interior surfaces slabs, and is continuous, in effect, throughout the length and width of the slabs. The nonhardening, waterproof material used for the expansion joints also provides thermal, acoustic,

or other vibration insulation and also serves as'.

a sealagainst moisture and dampness at all points where it v,might otherwise penetrate to the inner section of the slab. The inner and outer' sections of each slab may expand and contract toward and away from each other and in a sliding or shearing fashion and yet the two sections of the slab are structurally united and tied together by the reinforcingvstruts.v The improved slab might be thought of as a structural sandwich in which each of the two slices or sections is completely lined at its inner channeled'or recessed face with waterproofed brous material (the sheets which form Vthe hollow core members and any sheets which complete their continuity), and sandwiched between these lined sections, at all places where they come'together, is the filling of plastic non-hardening waterproof material. .In some cases the plastic non-hardening material may be omittedso that at all the desired shape, or semi-formed, orf-shapedfto the desired configuration during castingofthe' slab. Their iiexibility makes it vpossible,tofuse them for almost any practical requirexriertv's` asl to form as they can beproperly adjustedandfshaped during casting of the slab. Their arched con--` struction increases the strength of the slabI and materially lessens its weight and `cost ofy production. The amount of concrete .employed is reduced to a minimum. -1

The term concrete as used throughout the. specification and claims is intended to include anyy equivalent self-hardening, plastic material, sucl'rf as gypsum and similar materials ordinarily used in the construction of buildings.

While I have described the fabrication of ni improved slab bythe horizontal table `me'thod, which produces a slab `suitable for use in the erection of so-called prefabricated buildings, it will be understood that the invention is not limited to a slab made by that method. The invention includes slabs of such construction that they may, if desired, be fabricated in situ as the construction of the building progressesin accordance with the usual building methods or other appropriate ones. y

I claim 1. A composite building slab comprising a body of concrete divided into two sections along a median plane lying parallel with its major faces, the interior face of each of. said sections having depressions which cooperate with the corresponding depressions in'the other slab section to form interior openings in vthe composite slab, sheet material lining substantiallyvthe entire inner face Y of each slab section, non-hardening waterproof plastic material interposedbetween thev sheet material at all points where portions of the two slab sections come together, and reinforcing elements tying the two slab sections together.

2. A composite building slab comprising a body of concrete divided into two sections along a median plane lying parallel with its major faces, the interior face of each of said sections having depressions which cooperate with the corresponding depressions in the other section to form interior openings in the composite slab, waterproofed brous material lining substantially the entire inner face of each slab section, non-hardening waterproof plastic material interposed between' the waterproofed fibrous material at all points where portions .of the two slab sections come together, and reinforcing elements vtying the two slab sections together.`

3 A composite building slab comprising a body of concrete divided into two sections along a median 'plane lying parallel with its major faces, the interior face of atleast one of said sections having depressions which form interior openings in the composite slab, sheet material lining substantiallyrthe entire *face of each slab section, non-hardening waterproof plastic material interposed between the sheet material at all points where portions of the two slab sections come together, and reinforcing elements tying the two slab sections together.

` ,4. A composite building slab comprising a body of concrete divided into two sections along a median plane lying parallel with its major faces,

the interior face of at least one of said sections having depressions which form interior openings in the composite slab, waterproofed brous 10 material lining substantially the entire inner face of each slab section, non-hardening waterproof plastic material interposed between the'waterproofedbrous material at all points where portions of the two slab sections. come together. and

l5 reinforcing elements tying the two slab sections- 5. A building slab comprising a body of concrete, a metallic reinforcing structure embedded `,inffthejconcrete, and means for clamping the slab ftola-similar slab comprising at least one metal ,mer ber rigidlysecured to a part of the metallic `reinorcing` structure and means for clamping said metal member to the corresponding metaly member of another slab whereby the clamping forces react against said metal member and the metallic reinforcing structure.

6. A building slab comprising a body of con-v crete having interior openings, a metallic reinforcing structure embedded in the concrete having transverse strut elements, at least one metal member rigidly secured Ato one .of-said transverse strut elements and projecting into one of said interior openings, one of the walls of the slab having a hand hole communicating with the same interior opening near said metal member, and means for clamping said .metal member to a corresponding metal member. in an adjoining slab.

7. A building slab 'comprising a body of con- 40 crete having interior openings, `a metallic reinforcing-structure embedded in the concrete, and means for clamping the slab to an adjoining one comprising instrumentalities entirely concealed :within Vtheslab and including atleast one metal member rigidly secured to they metallic rein'- forcing structure and which projects into one of said ,interior-openings', one of the walls ofthe slab having ahand-hole communicating with the same interioropenng', to permit access to said metal member, yand'means for clamping saidv metal member'tola corresponding metal member in an adjoining 'slab.' y

8. A building slab in accordance with claim 7 in which said vmetal member is provided with a bolt hole and in'which `a tube 'cast -in the concrete extends from said bolt hole to the end of the slab to receive a bolt.

9. A building' slab comprising a bodyofcncrete, a metallic reinforcement embe`dde\d inthe concrete all elements of which are rigidly secured together to form a unitary structure, and means for clamping the slab to a similar slab comprising at least one metal member rigidly secured'to `a part of the unitary reinforcing structure and a bolt for clamping said metal member to the corresponding metal member of another slab whereby the clamping Aforces react against said metal member and the metallic reinforcing structure 1 and whereby the metal structure is substantially continuous throughoufalfth'e slabs that are bolted together.

10. A composite building slab comprising a,

' body of concrete divided into two sections along a median plane lying parallely with itsA major faces, the interior face of each of saidsections having depressions which cooperate with the -corresponding depressions in the other slab section to form interior openings in the composite slab, hollow core members cast within and IiningIsaid' interior openings in` vthe slab, `non-hardening 5 waterproof plastic material interposed Abetween those portions of the slabs'ections that come into closest proximity, and Areinforcing elements tying. the two slab sectionstogether. .i2

11, A cellular concrete member suitablefor use' 'l0 in the erection'of a prefabricated building, said member. being slab-like in forml so that a number of such members may bedirectly connectedA together at their edge portions to constitute, the walls, partitions, floors and roof of the building, 15 one of the walls of said member being provided with a,bolt hole extending from the exterior of the member to one of the cells-in the member.

and one of the walls of lthe mem-ber having hand hole in the vicinity of the bolt hole whereby 20 two of the slab-like vmembers may be bolted to gether through the bolt holes of the two members by the access afforded by the hand holes.

12.,A cellular concrete member in accordance with claim 11 in which the bolt hole is formed by 2 a tube cast in the concrete.

13. A cellular concrete member suitable for use in the erection of prefabricated buildings which is slab-like in form so that a numberl of such members may be connected together-to form the 30 walls, partitions, floors and roof of the building, said member having a metallic reinforcement embedded in the concreteand a unitary part of which lies within one of the cells of the member,

Cir

one of the walls of said member having a bolt 35 'Y hole extending from the exterior of the member to said cell and to said part of the metallic rein'- forcement, said part of the reinforcement having a bolt hole in alignment with the rst mentioned bolt hole, and one of the walls of said member 40 having a hand hole in the vicinity of said bolt holes whereby two of said members may be bolted" together through the bolt holes in the two members by reason of the accessail'orded by the` hand holes and whereby the bolting means will 45 react against the metallic reinforcements.

1'4, In a building, at least two concrete slabs adapted to be clamped together to form at least a portion of a wall, partition, oor or roof, each of said slabs having a metallic reinforcement em- 50 bedded in the concrete all elements of which are rigidly secured together to form a unitary structure, and means for clamping the adjoining slabs together comprising metallic retracting means reacting yagainst; the metallic 'reinforcements of 55 the two adjoining slabs in a direction such as to retract the metallic reinforcement of one slab 'steward the metallic reinforcement of the adjoinlng vwslab, whereby the I l y clamping forces are received-bythe metallic reinforcements and where- 60 by the metaly structure is substantially continuous throughout all the slabs that are clamped together.

15. A composite building slab comprising a body of concrete divided into two sections along 65 a median plane lying parallel with its major faces, the interior face of at least one of said sections having depressions which form interior openings in the composite slab, non-hardening waterproof plastic material interposed between those. por-` 70 tions of the slab sections, that come into closest proximity, and reinforcing elements tying the twoslab sections together.

16. A cellular concrete member suitable for use .in the erection of a-prefabrlcated building, said 75 member being slab-like in form soy that a number of such members may be directly connected together at their edge portions to constitute the walls, partitions, oors and roof of the building, one of the walls of said member having a hand hole communicating with one of the cells in the member, and clamping means whereby two of the slab-like members may be connected together at their meeting edge portions,said clamping means being concealed within the members when they are clamped through said hand hole.

MAURICE DEUTSCH.

together and being accessible 

